[chromecast] Enable Mojo javascript bindings for cast_shell

chromecast/renderer/cast_content_renderer_client.h

Index: chromecast/renderer/cast_content_renderer_client.h
diff --git a/chromecast/renderer/cast_content_renderer_client.h b/chromecast/renderer/cast_content_renderer_client.h
index 801474fb4ac9778516afaea7fe6bb3749bdd3e0f..e6599ba46eb5bcf2f4684d1a954c16cbf6d76680 100644
--- a/chromecast/renderer/cast_content_renderer_client.h
+++ b/chromecast/renderer/cast_content_renderer_client.h
@@ -25,6 +25,7 @@ class MediaCapsObserverImpl;
 }
 
 namespace shell {
+class CastGinRunner;
 class CastRenderThreadObserver;
 
 class CastContentRendererClient : public content::ContentRendererClient {
@@ -51,10 +52,14 @@ class CastContentRendererClient : public content::ContentRendererClient {
   void DeferMediaLoad(content::RenderFrame* render_frame,
                       bool render_frame_has_played_media_before,
                       const base::Closure& closure) override;
+  void RunScriptsAtDocumentStart(content::RenderFrame* render_frame) override;
 
  protected:
   CastContentRendererClient();
 
+  static void ExecuteJavaScript(content::RenderFrame* render_frame,
+                                int resourceId);
+
  private:
   std::unique_ptr<network_hints::PrescientNetworkingDispatcher>
       prescient_networking_dispatcher_;